According to Third Generation Partnership Project (3GPP) Technical Specification 25.331, a User Equipment (UE) can initiate a signaling connection using an initial direct transfer (IDT) procedure that includes calculating a START value for a security mode command procedure. This START value is sent from the UE to its communicating network, and the network uses the received START value to initialize a COUNT-I variable that is used for integrity protection of messages between the UE and the network.
If, however, connection failures cause a signal connection release prior to the security mode command procedure completing, the START value sent in an IDT may not be the same as the START value used at the UE, and the integrity check for messages could fail. Subsequent attempts to establish a replacement connection using the IDT procedure will also fail due to an inability to sustain integrity protection.
There is an opportunity for a UE to compensate for COUNT mismatches to improve the chances that a replacement connection will succeed. The various aspects, features and advantages of the disclosure will become more fully apparent to those having ordinary skill in the art upon careful consideration of the following Drawings and accompanying Detailed Description.